Many challenges arise in the production, transportation, and refining of heavy and extra-heavy crude oil as compared to light crude oil. The high viscosity of heavy and extra-heavy crude oil results in the need for alternative methods of extraction, e.g., steam injection. Additionally, the increased viscosity renders it difficult to flow through pipelines. Further, asphaltenes and paraffins within the heavy and extra-heavy crude oil can create deposits which can pose numerous problems. As a result, these crude oils pose an economic challenge to produce.
Commonly, a diluent is added continuously or at regular intervals during the production and transportation processes to maintain the flowability of the heavy and extra-heavy oil. Various diluents can be used for reducing the viscosity; however, the type of diluent determines the amount needed. For example, more synthetic crude oil is needed as compared to natural gas condensate to achieve the same viscosity reduction. The addition of more diluent can be a challenge in the refinement process, and represents a significant operational cost.
The viscosity of the crude oil has an impact on several operating characteristics including pump pressure and temperature. A method for reducing the viscosity of crude oil is to increase the operating and transportation temperatures to maintain the liquid state of the crude oil; however, this increases the cost of production.
Asphaltenes are highly prevalent in heavy and extra-heavy crude oils, thus requiring special attention during the extraction and processing of these crude oils. Asphaltene deposits can block reservoir pores in near-well formations, production tubing, and downstream pipelines.
Therefore, a need exists to develop alternative methods and chemistries for reducing the viscosity of heavy and extra-heavy crude oils.